Enforce a timeout on interceptor isActive checks to fix Docker issue

Previously if Docker was unresponsive for some reason, this could run
forever, which would completely block UI startup. Not great!

This also improves the setup generally so it handles sync errors
automatically, simplifying the metadata fallback case slightly.

Author: pimterry

src/api-server.ts

@@ -96,9 +96,9 @@ const typeDefs = gql`
 `;
 
 // Wait for a promise, falling back to defaultValue on error or timeout
-const withFallback = <R>(p: Promise<R>, timeoutMs: number, defaultValue: R) =>
+const withFallback = <R>(p: () => Promise<R>, timeoutMs: number, defaultValue: R) =>
     Promise.race([
-        p.catch((error) => {
+        p().catch((error) => {
             reportError(error);
             return defaultValue;
         }),
@@ -196,18 +196,17 @@ const buildResolvers = (
         Interceptor: {
             isActivable: (interceptor: Interceptor) => {
                 return withFallback(
-                    interceptor.isActivable(),
+                    async () => interceptor.isActivable(),
                     interceptor.activableTimeout || INTERCEPTOR_TIMEOUT,
                     false
                 );
             },
             isActive: async (interceptor: Interceptor, { proxyPort }: { proxyPort: number }) => {
-                try {
-                    return await interceptor.isActive(proxyPort);
-                } catch (e) {
-                    reportError(e);
-                    return false;
-                }
+                return withFallback(
+                    async () => interceptor.isActive(proxyPort),
+                    INTERCEPTOR_TIMEOUT,
+                    false
+                );
             },
             metadata: async function (interceptor: Interceptor, { type }: { type?: 'DETAILED' | 'SUMMARY' }) {
                 if (!interceptor.getMetadata) return undefined;
@@ -220,16 +219,11 @@ const buildResolvers = (
                     ? INTERCEPTOR_TIMEOUT
                     : INTERCEPTOR_TIMEOUT * 10; // Longer timeout for detailed metadata
 
-                try {
-                    return await withFallback(
-                        interceptor.getMetadata(metadataType),
-                        timeout,
-                        undefined
-                    );
-                } catch (e) {
-                    reportError(e);
-                    return undefined;
-                }
+                return withFallback(
+                    async () => interceptor.getMetadata!(metadataType), // ! because we checked this above
+                    timeout,
+                    undefined
+                );
             }
         },