feat: Add stacktrace printing function

Author: hyperupcall

README.md

@@ -47,6 +47,12 @@ I suppose it can look redundant (compared to `if ! fn; then :; fi`), but it can
 - `core.err_clear`
 - `core.err_exists`
 
+## `stacktrace`
+
+Prints the stack trace. Recommended to use with `core.trap_add`
+
+- `core.stacktrace_print`
+
 Example
 
 ```sh

pkg/lib/public/stacktrace.sh

@@ -0,0 +1,11 @@
+# shellcheck shell=bash
+
+# @description Prints stacktrace
+core.stacktrace_print() {
+	printf '%s\n' 'Stacktrace:'
+
+	local i=
+	for ((i=0; i<${#FUNCNAME[@]}-1; ++i)); do
+		printf '%s\n' "  in ${FUNCNAME[$i]} (${BASH_SOURCE[$i]}:${BASH_LINENO[$i-1]})"
+	done; unset -v i
+} >&2