fix(install): don't attempt to cache specifiers that point to directories (#26369)

Fixes https://github.com/denoland/deno/issues/26162

cli/tools/registry/pm/cache_deps.rs

@@ -75,6 +75,13 @@ pub async fn cache_top_level_deps(
           if entry.key.ends_with('/') && specifier.as_str().ends_with('/') {
             continue;
           }
+          if specifier.scheme() == "file" {
+            if let Ok(path) = specifier.to_file_path() {
+              if !path.is_file() {
+                continue;
+              }
+            }
+          }
           roots.push(specifier.clone());
         }
       }

tests/specs/install/import_map_with_dir/__test__.jsonc

@@ -0,0 +1,9 @@
+{
+  "tempDir": true,
+  "steps": [
+    {
+      "args": "install",
+      "output": ""
+    }
+  ]
+}

tests/specs/install/import_map_with_dir/deno.json

@@ -0,0 +1,5 @@
+{
+  "imports": {
+    "@assets": "./src/assets/"
+  }
+}