Fix import statement completions followed by interface declaration (#50350)

* Fix import statement completions followed by interface declaration

* Fix stuff

* Linty

* Fix when named imports is missing closing brace

Author: andrewbranch

src/compiler/checker.ts

@@ -41414,7 +41414,7 @@ namespace ts {
                     }
                     else {
                         Debug.assert(node.kind !== SyntaxKind.VariableDeclaration);
-                        const importDeclaration = findAncestor(node, or(isImportDeclaration, isImportEqualsDeclaration)) as ImportDeclaration | ImportEqualsDeclaration | undefined;
+                        const importDeclaration = findAncestor(node, or(isImportDeclaration, isImportEqualsDeclaration));
                         const moduleSpecifier = (importDeclaration && tryGetModuleSpecifierFromDeclaration(importDeclaration)?.text) ?? "...";
                         const importedIdentifier = unescapeLeadingUnderscores(isIdentifier(errorNode) ? errorNode.escapedText : symbol.escapedName);
                         error(

src/compiler/core.ts

@@ -2371,6 +2371,9 @@ namespace ts {
         return (arg: T) => f(arg) && g(arg);
     }
 
+    export function or<P, R1 extends P, R2 extends P>(f1: (p1: P) => p1 is R1, f2: (p2: P) => p2 is R2): (p: P) => p is R1 | R2;
+    export function or<P, R1 extends P, R2 extends P, R3 extends P>(f1: (p1: P) => p1 is R1, f2: (p2: P) => p2 is R2, f3: (p3: P) => p3 is R3): (p: P) => p is R1 | R2 | R3;
+    export function or<T extends unknown[], U>(...fs: ((...args: T) => U)[]): (...args: T) => U;
     export function or<T extends unknown[], U>(...fs: ((...args: T) => U)[]): (...args: T) => U {
         return (...args) => {
             let lastResult: U;