Fix linting and build errors.

src/app/input-form.tsx

@@ -1,16 +1,20 @@
-import {useState} from 'react';
-import ValidatingInputNumberField from "./validating-input-number-field.tsx";
-import {actionLoadedMaze, actionLoadingFailed, actionStartedLoading} from "./state/action.ts";
+import {ActionDispatch, FormEvent, useState} from 'react';
+import ValidatingInputNumberField, {ValidatorFunction} from "./validating-input-number-field.tsx";
+import {Action, actionLoadedMaze, actionLoadingFailed, actionStartedLoading} from "./state/action.ts";
 import styles from "./input-form.module.css";
 import "./input-form.css";
+import {State} from "@/app/state/state.ts";
 
-export default function InputForm({state, dispatch}) {
+export default function InputForm({state, dispatch}: {
+    state: State,
+    dispatch: ActionDispatch<[Action]>
+}) {
     const [width, setWidth] = useState(10);
     const [height, setHeight] = useState(10);
-    const [id, setId] = useState(null as number);
+    const [id, setId] = useState<number>();
     const [algorithm, setAlgorithm] = useState('wilson');
 
-    const handleSubmit = (e) => {
+    const handleSubmit = (e: FormEvent) => {
         e.preventDefault();
         dispatch(actionStartedLoading());
         const url = `https://manuel.friedli.info/labyrinth/create/json?w=${width}&h=${height}&id=${id || ''}&algorithm=${algorithm}`;
@@ -25,38 +29,42 @@ export default function InputForm({state, dispatch}) {
                 dispatch(actionLoadingFailed(reason));
             });
     };
-    const validateWidthHeightInput = value => {
-        if (isNaN(value) || "" === value || (Math.floor(value) !== Number(value))) {
+    const validateWidthHeightInput: ValidatorFunction<string, number> = value => {
+        const numberValue = Number(value);
+        if (isNaN(numberValue) || "" === value || (Math.floor(numberValue) !== numberValue)) {
             return {
                 valid: false,
-                message: "Must be an integer greater than 1.",
-                value
+                message: "Must be an integer greater than 1."
             };
         }
-        if (value < 1) {
+        if (numberValue < 1) {
             return {
                 valid: false,
-                message: "Must be greater than 1.",
-                value
+                message: "Must be greater than 1."
             };
         }
         return {
             valid: true,
-            value
+            value: numberValue
         };
     };
-    const validateIdInput = value => {
+    const validateIdInput: ValidatorFunction<string, number> = value => {
+        if ("" === value) {
+            return {
+                valid: true
+            };
+        }
+        const numberValue = Number(value);
         // FIXME doesn't handle strings with characters correctly (e.g. "asdf" yields an empty value, due to "type=number").
-        if (isNaN(value) || ("" !== value && ((Math.floor(value) !== Number(value))))) {
+        if (isNaN(numberValue) || Math.floor(numberValue) !== numberValue) {
             return {
                 valid: false,
-                message: "Must be empty or an integer",
-                value
+                message: "Must be empty or an integer"
             };
         }
         return {
             valid: true,
-            value
+            value: numberValue
         }
     };
     return (