Remove catch-all handler from make_canonicalize_path_error_handlers

A user of make_canonicalize_path_error_handlers might want to have its
own catch-all handler. Remove the catch-all handler from
make_canonicalize_path_error_handlers to give callers more flexibility.

Author: strager

src/file-canonical.cpp

@@ -714,7 +714,11 @@ sloppy_result<canonical_path_result> canonicalize_path_sloppy(
       make_canonicalize_path_error_handlers([](std::string &&message) {
         return sloppy_result<canonical_path_result>::failure(
             std::move(message));
-      }));
+      }),
+      []() {
+        QLJS_ASSERT(false);
+        return sloppy_result<canonical_path_result>::failure("unknown error");
+      });
 }
 
 sloppy_result<canonical_path_result> canonicalize_path_sloppy(

src/quick-lint-js/file-canonical.h

@@ -165,12 +165,6 @@ auto make_canonicalize_path_error_handlers(const Func &handle_error) {
         QLJS_ASSERT(false);  // One of the above handlers should have handled
                              // the error already.
         return handle_error("failed to canonicalize path"s);
-      },
-      [handle_error]() {
-        // TODO(strager): Get rid of this handler.
-        QLJS_ASSERT(false);  // One of the above handlers should have handled
-                             // the error already.
-        return handle_error("failed to canonicalize path"s);
       });
 }
 }

test/test-file-canonical.cpp

@@ -83,9 +83,11 @@ boost::leaf::result<void> canonicalize_expecting_failure(const Path& path) {
 }
 
 auto fail_test_error_handlers() {
-  return make_canonicalize_path_error_handlers([](const std::string& message) {
-    ADD_FAILURE() << "error: " << message;
-  });
+  return std::tuple(
+      make_canonicalize_path_error_handlers([](const std::string& message) {
+        ADD_FAILURE() << "error: " << message;
+      }),
+      []() { ADD_FAILURE() << "unknown error"; });
 }
 
 bool process_ignores_filesystem_permissions() noexcept {