server: add error handling when did resolution fails && add statusText to responses

src/user.ts

···
     console.error(e);
     return new Response("Something went wrong loading this route", {
       status: 500,
+      statusText: "Internal Server Error",
     });
   }
 }
···
     } catch {
       return new Response("Failed to resolve handle", {
         status: 500,
+        statusText: "Internal Server Error",
       });
     }
   } else did = user.did;
 
   // resolve did doc
-  const doc = await docResolver.resolve(did);
+  let doc;
+  try {
+    doc = await docResolver.resolve(did);
+  } catch {
+    return new Response("Could not resolve " + did + ".\n", {
+      status: 500,
+      statusText: "Internal Server Error",
+    });
+  }
 
   // handle must be in did document
   if ("handle" in user && !doc.alsoKnownAs?.includes(`at://${user.handle}`)) {
···
       `Provided handle (at://${user.handle}) was not found in the did document for ${did}. Found handles:\n${doc.alsoKnownAs?.map((x) => "- " + x).join("\n") ?? "None"}`,
       {
         status: 500,
+        statusText: "Internal Server Error",
       }
     );
   }
···
       `Could not find a valid pds for ${"handle" in user ? user.handle : user.did}`,
       {
         status: 500,
+        statusText: "Internal Server Error",
       }
     );