Started textnodes, renamed tool with wrong name, started field configuration system

source/errors.mjs

@@ -1,5 +1,18 @@
 import { inspect } from 'node:util';
 
+// § GROUP: Configuration field errors
+
+export class Invalid_Data extends Error {
+	constructor(data) {
+		const { value, target, expected, validator, name } = data;
+		const type = value === null ? 'null' : typeof value;
+		const target_info = target ? inspect(target) : 'unknown target';
+		const expected_desc = expected ?? `data that would pass validation using ${validator}`;
+		super(`Data validation failed for field "${name}" of ${target_info}. Encountered data of type "${type}" while expecting "${expected_desc}".`);
+		this.data = data;
+	}
+}
+
 // § GROUP: Resolving errors
 
 export class Item_Unresolvable extends Error {