diff --git a/src/slang-nodes/ArgumentsDeclaration.ts b/src/slang-nodes/ArgumentsDeclaration.ts
index b896b17ed..a6b8f0988 100644
--- a/src/slang-nodes/ArgumentsDeclaration.ts
+++ b/src/slang-nodes/ArgumentsDeclaration.ts
@@ -18,7 +18,7 @@ function createNonterminalVariant(
     return new NamedArgumentsDeclaration(variant, options);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class ArgumentsDeclaration extends SlangNode {
diff --git a/src/slang-nodes/ContractMember.ts b/src/slang-nodes/ContractMember.ts
index 71d2ccebb..2a109000b 100644
--- a/src/slang-nodes/ContractMember.ts
+++ b/src/slang-nodes/ContractMember.ts
@@ -62,7 +62,7 @@ function createNonterminalVariant(
     return new UserDefinedValueTypeDefinition(variant);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class ContractMember extends SlangNode {
diff --git a/src/slang-nodes/ContractSpecifier.ts b/src/slang-nodes/ContractSpecifier.ts
index e8498bfb3..aa55bb401 100644
--- a/src/slang-nodes/ContractSpecifier.ts
+++ b/src/slang-nodes/ContractSpecifier.ts
@@ -18,7 +18,7 @@ function createNonterminalVariant(
     return new StorageLayoutSpecifier(variant, options);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class ContractSpecifier extends SlangNode {
diff --git a/src/slang-nodes/Expression.ts b/src/slang-nodes/Expression.ts
index 32b746a42..7d9468628 100644
--- a/src/slang-nodes/Expression.ts
+++ b/src/slang-nodes/Expression.ts
@@ -123,7 +123,7 @@ function createNonterminalVariant(
     return extractVariant(new ElementaryType(variant));
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class Expression extends SlangNode {
diff --git a/src/slang-nodes/FallbackFunctionAttribute.ts b/src/slang-nodes/FallbackFunctionAttribute.ts
index e696e7e41..735d47ab8 100644
--- a/src/slang-nodes/FallbackFunctionAttribute.ts
+++ b/src/slang-nodes/FallbackFunctionAttribute.ts
@@ -22,7 +22,7 @@ function createNonterminalVariant(
     return new OverrideSpecifier(variant);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class FallbackFunctionAttribute extends SlangNode {
diff --git a/src/slang-nodes/ForStatementInitialization.ts b/src/slang-nodes/ForStatementInitialization.ts
index a26489a0f..94174c051 100644
--- a/src/slang-nodes/ForStatementInitialization.ts
+++ b/src/slang-nodes/ForStatementInitialization.ts
@@ -29,7 +29,7 @@ function createNonterminalVariant(
     return new TupleDeconstructionStatement(variant, options);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class ForStatementInitialization extends SlangNode {
diff --git a/src/slang-nodes/FunctionAttribute.ts b/src/slang-nodes/FunctionAttribute.ts
index a4d36f472..689dd070a 100644
--- a/src/slang-nodes/FunctionAttribute.ts
+++ b/src/slang-nodes/FunctionAttribute.ts
@@ -22,7 +22,7 @@ function createNonterminalVariant(
     return new OverrideSpecifier(variant);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class FunctionAttribute extends SlangNode {
diff --git a/src/slang-nodes/ImportClause.ts b/src/slang-nodes/ImportClause.ts
index 58f3cd96b..fb5ff8a92 100644
--- a/src/slang-nodes/ImportClause.ts
+++ b/src/slang-nodes/ImportClause.ts
@@ -22,7 +22,7 @@ function createNonterminalVariant(
     return new ImportDeconstruction(variant, options);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class ImportClause extends SlangNode {
diff --git a/src/slang-nodes/MappingKeyType.ts b/src/slang-nodes/MappingKeyType.ts
index 4aa3cbd95..06f1087e5 100644
--- a/src/slang-nodes/MappingKeyType.ts
+++ b/src/slang-nodes/MappingKeyType.ts
@@ -15,7 +15,7 @@ function createNonterminalVariant(
     return new IdentifierPath(variant);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class MappingKeyType extends SlangNode {
diff --git a/src/slang-nodes/Pragma.ts b/src/slang-nodes/Pragma.ts
index 9d06b2a43..276555fe1 100644
--- a/src/slang-nodes/Pragma.ts
+++ b/src/slang-nodes/Pragma.ts
@@ -22,7 +22,7 @@ function createNonterminalVariant(
     return new VersionPragma(variant);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class Pragma extends SlangNode {
diff --git a/src/slang-nodes/ReceiveFunctionAttribute.ts b/src/slang-nodes/ReceiveFunctionAttribute.ts
index 9745d34fb..608df0894 100644
--- a/src/slang-nodes/ReceiveFunctionAttribute.ts
+++ b/src/slang-nodes/ReceiveFunctionAttribute.ts
@@ -22,7 +22,7 @@ function createNonterminalVariant(
     return new OverrideSpecifier(variant);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class ReceiveFunctionAttribute extends SlangNode {
diff --git a/src/slang-nodes/SourceUnitMember.ts b/src/slang-nodes/SourceUnitMember.ts
index 07e74b736..aeeb129aa 100644
--- a/src/slang-nodes/SourceUnitMember.ts
+++ b/src/slang-nodes/SourceUnitMember.ts
@@ -62,7 +62,7 @@ function createNonterminalVariant(
     return new EventDefinition(variant, options);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class SourceUnitMember extends SlangNode {
diff --git a/src/slang-nodes/Statement.ts b/src/slang-nodes/Statement.ts
index 783ed3ac5..efc3c95f0 100644
--- a/src/slang-nodes/Statement.ts
+++ b/src/slang-nodes/Statement.ts
@@ -78,7 +78,7 @@ function createNonterminalVariant(
     return new UncheckedBlock(variant, options);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class Statement extends SlangNode {
diff --git a/src/slang-nodes/StringExpression.ts b/src/slang-nodes/StringExpression.ts
index 7dac815db..d51d5ed88 100644
--- a/src/slang-nodes/StringExpression.ts
+++ b/src/slang-nodes/StringExpression.ts
@@ -30,7 +30,7 @@ function createNonterminalVariant(
     return new UnicodeStringLiterals(variant, options);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class StringExpression extends SlangNode {
diff --git a/src/slang-nodes/TupleMember.ts b/src/slang-nodes/TupleMember.ts
index 4eb3bbe0b..e3361c478 100644
--- a/src/slang-nodes/TupleMember.ts
+++ b/src/slang-nodes/TupleMember.ts
@@ -18,7 +18,7 @@ function createNonterminalVariant(
     return new UntypedTupleMember(variant);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class TupleMember extends SlangNode {
diff --git a/src/slang-nodes/TypeName.ts b/src/slang-nodes/TypeName.ts
index e4868c37a..a04ee7639 100644
--- a/src/slang-nodes/TypeName.ts
+++ b/src/slang-nodes/TypeName.ts
@@ -31,7 +31,7 @@ function createNonterminalVariant(
     return new IdentifierPath(variant);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class TypeName extends SlangNode {
diff --git a/src/slang-nodes/UsingClause.ts b/src/slang-nodes/UsingClause.ts
index e619b60c9..38e951b20 100644
--- a/src/slang-nodes/UsingClause.ts
+++ b/src/slang-nodes/UsingClause.ts
@@ -14,7 +14,7 @@ function createNonterminalVariant(
     return new UsingDeconstruction(variant);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class UsingClause extends SlangNode {
diff --git a/src/slang-nodes/VersionExpression.ts b/src/slang-nodes/VersionExpression.ts
index 1385e3ee3..d0661724d 100644
--- a/src/slang-nodes/VersionExpression.ts
+++ b/src/slang-nodes/VersionExpression.ts
@@ -14,7 +14,7 @@ function createNonterminalVariant(
     return new VersionTerm(variant);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class VersionExpression extends SlangNode {
diff --git a/src/slang-nodes/YulExpression.ts b/src/slang-nodes/YulExpression.ts
index 66de092bd..dd697cc5c 100644
--- a/src/slang-nodes/YulExpression.ts
+++ b/src/slang-nodes/YulExpression.ts
@@ -23,7 +23,7 @@ function createNonterminalVariant(
     return new YulPath(variant);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class YulExpression extends SlangNode {
diff --git a/src/slang-nodes/YulLiteral.ts b/src/slang-nodes/YulLiteral.ts
index 72ef74856..a14f8ee5b 100644
--- a/src/slang-nodes/YulLiteral.ts
+++ b/src/slang-nodes/YulLiteral.ts
@@ -22,7 +22,7 @@ function createNonterminalVariant(
     return new StringLiteral(variant, options);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class YulLiteral extends SlangNode {
diff --git a/src/slang-nodes/YulStatement.ts b/src/slang-nodes/YulStatement.ts
index 6d711899c..88a693eb7 100644
--- a/src/slang-nodes/YulStatement.ts
+++ b/src/slang-nodes/YulStatement.ts
@@ -63,7 +63,7 @@ function createNonterminalVariant(
     return extractVariant(new YulExpression(variant, options));
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class YulStatement extends SlangNode {
diff --git a/src/slang-nodes/YulSwitchCase.ts b/src/slang-nodes/YulSwitchCase.ts
index 3c629e55b..aaba336e4 100644
--- a/src/slang-nodes/YulSwitchCase.ts
+++ b/src/slang-nodes/YulSwitchCase.ts
@@ -18,7 +18,7 @@ function createNonterminalVariant(
     return new YulValueCase(variant, options);
   }
   const exhaustiveCheck: never = variant;
-  return exhaustiveCheck;
+  throw new Error(`Unexpected variant: ${JSON.stringify(exhaustiveCheck)}`);
 }
 
 export class YulSwitchCase extends SlangNode {