tools: remove panics in favor of errors in `v bump` (#19066)

cmd/tools/vbump.v

@@ -73,10 +73,10 @@ fn get_replacement_function(options Options) ReplacementFunction {
 	return replace_with_increased_patch_version
 }
 
-fn process_file(input_file string, options Options) {
-	lines := os.read_lines(input_file) or { panic('Failed to read file: ${input_file}') }
+fn process_file(input_file string, options Options) ! {
+	lines := os.read_lines(input_file) or { return error('Failed to read file: ${input_file}') }
 
-	mut re := regex.regex_opt(semver_query) or { panic('Could not create a RegEx parser.') }
+	mut re := regex.regex_opt(semver_query) or { return error('Could not create a RegEx parser.') }
 
 	repl_fn := get_replacement_function(options)
 
@@ -110,11 +110,11 @@ fn process_file(input_file string, options Options) {
 	os.rm(backup_file) or {}
 
 	// Rename the original to the backup.
-	os.mv(input_file, backup_file) or { panic('Failed to copy file: ${input_file}') }
+	os.mv(input_file, backup_file) or { return error('Failed to copy file: ${input_file}') }
 
 	// Process the old file and write it back to the original.
 	os.write_file(input_file, new_lines.join_lines()) or {
-		panic('Failed to write file: ${input_file}')
+		return error('Failed to write file: ${input_file}')
 	}
 
 	// Remove the backup file.
@@ -129,7 +129,7 @@ fn process_file(input_file string, options Options) {
 
 fn main() {
 	if os.args.len < 2 {
-		println('Usage: ${tool_name} [options] [file1 file2 ...]
+		eprintln('Usage: ${tool_name} [options] [file1 file2 ...]
 ${tool_description}
 Try ${tool_name} -h for more help...')
 		exit(1)
@@ -152,7 +152,7 @@ Try ${tool_name} -h for more help...')
 	}
 
 	remaining := fp.finalize() or {
-		println(fp.usage())
+		eprintln(fp.usage())
 		exit(1)
 	}
 
@@ -161,24 +161,33 @@ Try ${tool_name} -h for more help...')
 		exit(0)
 	}
 
-	validate_options(options) or { panic(err) }
+	validate_options(options) or {
+		eprintln(fp.usage())
+		exit(1)
+	}
 
 	files := remaining[1..]
 
 	if files.len == 0 {
 		if !os.exists('v.mod') {
-			println('v.mod does not exist. You can create one using "v init".')
+			eprintln('v.mod does not exist. You can create one using "v init".')
+			exit(1)
+		}
+		process_file('v.mod', options) or {
+			eprintln('Failed to process v.mod: ${err}')
 			exit(1)
 		}
-		process_file('v.mod', options)
 	}
 
 	for input_file in files {
 		if !os.exists(input_file) {
-			println('File not found: ${input_file}')
+			eprintln('File not found: ${input_file}')
+			exit(1)
+		}
+		process_file(input_file, options) or {
+			eprintln('Failed to process ${input_file}: ${err}')
 			exit(1)
 		}
-		process_file(input_file, options)
 	}
 }