refactor(tsUtils): ignore ts files when searching for definitions

Author: jackofdiamond5

projects/igniteui-angular/migrations/common/tsUtils.ts

@@ -223,21 +223,33 @@ export function createProjectService(serverHost: tss.server.ServerHost): tss.ser
 export function getTypeDefinitionAtPosition(langServ: tss.LanguageService, entryPath: string, position: number): tss.DefinitionInfo | null {
     const definition = langServ.getDefinitionAndBoundSpan(entryPath, position)?.definitions[0];
     if (!definition) { return null; }
+
     // if the definition's kind is a reference, the identifier is a template variable referred in an internal/external template
     if (definition.kind.toString() === 'reference') {
         return langServ.getDefinitionAndBoundSpan(entryPath, definition.textSpan.start).definitions[0];
     }
     let typeDefs = langServ.getTypeDefinitionAtPosition(entryPath, definition.textSpan.start);
     // if there are no type definitions found, the identifier is a ts property, referred in an internal/external template
+    // or is a reference in a decorator
     if (!typeDefs) {
+        /*
+         normally, the tsserver will consider non .ts files as external to the project
+         however, we load .html files which we can handle with the Angular language service
+         here we're only looking for definitions in a .ts source file
+         we call the getSourceFile function which accesses a map of files, previously loaded by the tsserver
+         at this point the map contains all .html files that we've included
+         we have to ignore them, since the language service will attempt to parse them as .ts files
+        */
+        if (!definition.fileName.endsWith('.ts')) { return null; }
+
         const sourceFile = langServ.getProgram().getSourceFile(definition.fileName);
-        // if the language service cannot resolve the source, this means its not a .ts file
         if (!sourceFile) { return null; }
 
         const classDeclaration = sourceFile
             .statements
             .filter(<(a: tss.Statement) => a is tss.ClassDeclaration>(m => m.kind === tss.SyntaxKind.ClassDeclaration))
             .find(m => m.name.getText() === definition.containerName);
+
         // there must be at least one class declaration in the .ts file and the property must belong to it
         if (!classDeclaration) { return null; }