Improve script based on JB suggestion

gotestcov

@@ -2,20 +2,20 @@
 
 set -eu
 
+# find_go_mod walks up the directory tree looking for the go.mod file.
+# If it doesn't find it, the script will be aborted.
 find_go_mod() {
     cwd="$(pwd)"
 
-    while :; do
-        if [ -e "$cwd/go.mod" ]; then
-            echo $cwd
+    while [ "$cwd" != "/" ]; do
+        if [ -f "$cwd/go.mod" ]; then
+            echo "$cwd"
             return
-        elif [ "$cwd" = "/" ]; then
-            echo "E: go.mod not found in parent path. Aborting!"
-            exit 1
-        else
-            cwd="$(dirname "$cwd")"
         fi
+        cwd=$(dirname "$cwd")
     done
+    echo "Error: go.mod not found in parent path. Aborting!"
+    exit 1
 }
 
 projectroot="$(find_go_mod)"
@@ -43,10 +43,10 @@ go test -cover -covermode=set $@ -args -test.gocoverdir="${raw_cov_dir}"
 go tool covdata textfmt -i="${raw_cov_dir}" -o="${cov_dir}/coverage.out"
 
 # Append the Rust coverage data to the Go one
-cat "${raw_cov_dir}/rust-cov/rust2go_coverage" >> "${cov_dir}/coverage.out"
+cat "${raw_cov_dir}/rust-cov/rust2go_coverage" >>"${cov_dir}/coverage.out"
 
 # Filter out the testutils package and the pb.go file
-grep -v -e "testutils" -e "pb.go" "${cov_dir}/coverage.out" > "${cov_dir}/coverage.out.filtered"
+grep -v -e "testutils" -e "pb.go" "${cov_dir}/coverage.out" >"${cov_dir}/coverage.out.filtered"
 
 # Generate the HTML report
 go tool cover -o "${cov_dir}/index.html" -html="${cov_dir}/coverage.out.filtered"