(fix) svelte2tsx runtime error diagnostics line number (#1183)

- null check in checkIfImportIsEventDispatcher
- fix svelte2tsx runtime error diagnostics

#1182

Author: jasonlyu123

packages/language-server/src/plugins/typescript/DocumentSnapshot.ts

@@ -187,7 +187,7 @@ function preprocessSvelteFile(document: Document, options: SvelteSnapshotOptions
     } catch (e: any) {
         // Error start/end logic is different and has different offsets for line, so we need to convert that
         const start: Position = {
-            line: e.start?.line - 1 ?? 0,
+            line: (e.start?.line ?? 1) - 1,
             character: e.start?.column ?? 0
         };
         const end: Position = e.end ? { line: e.end.line - 1, character: e.end.column } : start;

packages/svelte2tsx/src/svelte2tsx/nodes/ComponentEvents.ts

@@ -382,7 +382,7 @@ function checkIfImportIsEventDispatcher(node: ts.ImportDeclaration): string | un
     }
 
     const namedImports = node.importClause?.namedBindings;
-    if (ts.isNamedImports(namedImports)) {
+    if (namedImports && ts.isNamedImports(namedImports)) {
         const eventDispatcherImport = namedImports.elements.find(
             // If it's an aliased import, propertyName is set
             (el) => (el.propertyName || el.name).text === 'createEventDispatcher'