fix(coverage): error if no files found (#21615)

This commit fixes a panic in `deno coverage` command if the file
to be covered doesn't produce any coverage data.

Fixes https://github.com/denoland/deno/issues/21580

3 files changed, 10 insertions, 1 deletions

diff --git a/cli/tests/integration/coverage_tests.rs b/cli/tests/integration/coverage_tests.rs
index 4c7a51f4e..497d67890 100644
--- a/cli/tests/integration/coverage_tests.rs
+++ b/cli/tests/integration/coverage_tests.rs
@@ -630,3 +630,9 @@ File         | Branch % | Line % |
 ",
   );
 }
+
+itest!(no_files_found {
+  args: "coverage doesnt_exist.js",
+  exit_code: 1,
+  output: "coverage/doesnt_exist.out",
+});
diff --git a/cli/tests/testdata/coverage/doesnt_exist.out b/cli/tests/testdata/coverage/doesnt_exist.out
new file mode 100644
index 000000000..0b679bcb4
--- /dev/null
+++ b/cli/tests/testdata/coverage/doesnt_exist.out
@@ -0,0 +1 @@
+error: No coverage files found
diff --git a/cli/tools/coverage/mod.rs b/cli/tools/coverage/mod.rs
index 28ecc100e..d951d5d5c 100644
--- a/cli/tools/coverage/mod.rs
+++ b/cli/tools/coverage/mod.rs
@@ -453,8 +453,10 @@ pub async fn cover_files(
 
   // Use the first include path as the default output path.
   let coverage_root = coverage_flags.files.include[0].clone();
-
   let script_coverages = collect_coverages(coverage_flags.files)?;
+  if script_coverages.is_empty() {
+    return Err(generic_error("No coverage files found"));
+  }
   let script_coverages = filter_coverages(
     script_coverages,
     coverage_flags.include,