Auto merge of #12535 - Manishearth:try-resource, r=KiChjang

Use Result instead of panicking when the resource dir can't be found

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #12520 (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [x] These changes do not require tests because it's a refactoring

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1 files changed, 6 insertions, 3 deletions

diff --git a/components/script/dom/userscripts.rs b/components/script/dom/userscripts.rs
index 25490fb7726..e1c071e83c7 100644
--- a/components/script/dom/userscripts.rs
+++ b/components/script/dom/userscripts.rs
@@ -24,9 +24,12 @@ pub fn load_script(head: &HTMLHeadElement) {
         let doc = doc.r();
 
         let path = if &**path_str == "" {
-            let mut p = resources_dir_path();
-            p.push("user-agent-js");
-            p
+            if let Ok(mut p) = resources_dir_path() {
+                p.push("user-agent-js");
+                p
+            } else {
+                return
+            }
         } else {
             PathBuf::from(path_str)
         };