throwing instead of returning a variable with type never (#1313)

Author: Janther

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 {

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 {

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 {

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 {

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 {

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 {

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 {

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 {

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 {

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 {