upgrade: Rust 1.39.0 (#3286)

.github/workflows/ci.yml

@@ -45,7 +45,7 @@ jobs:
       - name: Install rust
         uses: hecrj/setup-rust-action@v1
         with:
-          rust-version: "1.38.0"
+          rust-version: "1.39.0"
 
       - name: Install clippy and rustfmt
         if: matrix.kind == 'lint'

cli/compilers/ts.rs

@@ -580,7 +580,7 @@ impl SourceMapGetter for TsCompiler {
   fn get_source_map(&self, script_name: &str) -> Option<Vec<u8>> {
     self
       .try_to_resolve_and_get_source_map(script_name)
-      .and_then(|out| Some(out.source_code))
+      .map(|out| out.source_code)
   }
 
   fn get_source_line(&self, script_name: &str, line: usize) -> Option<String> {