style: improve backtrace format (rust-like)

src/mod/core.sh

@@ -16,7 +16,21 @@ std::backtrace() {
 	std::eprintln $'\033[4m'"Backtrace:"
 
 	for i in "${!FUNCNAME[@]}"; do
-		std::eprintln "  ${FUNCNAME[$i]} called at ${BASH_SOURCE[$i]}:${BASH_LINENO[$i - 1]}"
+		! [ "$i" -eq 0 ] || continue
+
+		std::eprintln "  $i: ${FUNCNAME[$i]}"
+
+		local src
+		src=$(realpath --relative-to "$PWD" -e "${BASH_SOURCE[$i]}")
+		if [ "${src:0:1}" != "." ]; then
+			src=./$src
+		fi
+
+		if [ "${BASH_LINENO[$i - 1]}" -eq 0 ]; then
+			std::eprintln $'\033[0m'"   at "$'\033[1;35m'"$src"
+		else
+			std::eprintln $'\033[0m'"   at "$'\033[1;35m'"$src:${BASH_LINENO[$i - 1]}"
+		fi
 	done
 }