config: add ErrorList file

src/config/ErrorList.zig

@@ -0,0 +1,23 @@
+const ErrorList = @This();
+
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+
+pub const Error = struct {
+    message: [:0]const u8,
+};
+
+/// The list of errors. This will use the arena allocator associated
+/// with the config structure (or whatever allocated used to call ErrorList
+/// functions).
+list: std.ArrayListUnmanaged(Error) = .{},
+
+/// True if there are no errors.
+pub fn empty(self: ErrorList) bool {
+    return self.list.items.len == 0;
+}
+
+/// Add a new error to the list.
+pub fn add(self: *ErrorList, alloc: Allocator, err: Error) !void {
+    try self.list.append(alloc, err);
+}