diff --git a/src/inputParser.ts b/src/inputParser.ts
index 808578b7..1d972607 100644
--- a/src/inputParser.ts
+++ b/src/inputParser.ts
@@ -140,18 +140,20 @@ const fromLegacy = (data: rawApiResponse[]): formattedComment[] => {
  * @return {formattedComment[]}
  */
 const fromLegacyOwner = (data: string): formattedComment[] => {
-  let data_: formattedComment[] = [],
+  const data_: formattedComment[] = [],
     comments = data.split("\n");
   for (let i = 0; i < comments.length; i++) {
-    let commentData = comments[i]!.split(":");
+    const value = comments[i];
+    if (!value) continue;
+    const commentData = value.split(":");
     if (commentData.length < 3) {
       continue;
     } else if (commentData.length > 3) {
       for (let j = 3; j < commentData.length; j++) {
-        commentData[2] += ":" + commentData[j];
+        commentData[2] += `:${commentData[j]}`;
       }
     }
-    let tmpParam: formattedComment = {
+    const tmpParam: formattedComment = {
       id: i,
       vpos: Number(commentData[0]),
       content: commentData[2] || "",
diff --git a/src/main.ts b/src/main.ts
index ed292914..cb3bd8bd 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -405,8 +405,8 @@ class NiconiComments {
       width_arr.push(measure.width);
     }
     const width = width_arr.reduce((p, c) => p + c, 0) / width_arr.length;
-    let width_max = Math.max(...width_arr),
-      width_min = Math.min(...width_arr),
+    let width_max = Math.max(...width_arr);
+    const width_min = Math.min(...width_arr),
       height =
         comment.fontSize *
           comment.lineHeight *
@@ -893,7 +893,7 @@ class NiconiComments {
    * @param vpos - 動画の現在位置の100倍 ニコニコから吐き出されるコメントの位置情報は主にこれ
    * @param forceRendering
    */
-  drawCanvas(vpos: number, forceRendering: boolean = false) {
+  drawCanvas(vpos: number, forceRendering = false) {
     const drawCanvasStart = performance.now();
     if (this.lastVpos === vpos && !forceRendering) return;
     this.lastVpos = vpos;
diff --git a/src/typeGuard.ts b/src/typeGuard.ts
index 91e2ab3e..a736eaf6 100644
--- a/src/typeGuard.ts
+++ b/src/typeGuard.ts
@@ -214,7 +214,7 @@ const typeGuard = {
   config: {
     initOptions: (item: unknown): item is InitOptions => {
       if (typeof item !== "object" || !item) return false;
-      const keys: { [key: string]: Function } = {
+      const keys: { [key: string]: (i: unknown) => boolean } = {
         useLegacy: isBoolean,
         formatted: isBoolean,
         showCollision: isBoolean,
@@ -227,16 +227,19 @@ const typeGuard = {
         config: typeGuard.config.config,
         format: (i: unknown) =>
           typeof i === "string" &&
-          i.match(
+          !!i.match(
             /^(niconicome|formatted|legacy|legacyOwner|owner|v1|default)$/
           ),
         video: (i: unknown) =>
           typeof i === "object" && (i as HTMLVideoElement).nodeName === "VIDEO",
       };
       for (const key in keys) {
+        console.log(keys[key]);
         if (
           (item as { [key: string]: unknown })[key] !== undefined &&
-          !(keys[key] as Function)((item as { [key: string]: unknown })[key])
+          !(keys[key] as (i: unknown) => boolean)(
+            (item as { [key: string]: unknown })[key]
+          )
         ) {
           console.warn(
             `[Incorrect input] var: initOptions, key: ${key}, value: ${
@@ -288,7 +291,7 @@ const typeGuard = {
           ) === 0
         );
       };
-      const keys: { [key: string]: Function } = {
+      const keys: { [key: string]: (i: unknown) => boolean } = {
         commentYPaddingTop: isNumber,
         commentYMarginBottom: isNumber,
         fpsInterval: isNumber,
@@ -301,6 +304,11 @@ const typeGuard = {
         sameCARange: isNumber,
         sameCAGap: isNumber,
         sameCAMinScore: isNumber,
+        contextStrokeOpacity: isNumber,
+        contextFillLiveOpacity: isNumber,
+        contextLineWidth: isNumber,
+        contextStrokeColor: isString,
+        contextStrokeInversionColor: isString,
         colors: (i: unknown) =>
           typeof i === "object" &&
           Object.keys(i as { [key: string]: unknown }).reduce(
@@ -325,9 +333,12 @@ const typeGuard = {
           ) === 0,
       };
       for (const key in item) {
+        console.log(key, item, keys);
         if (
           (item as { [key: string]: unknown })[key] !== undefined &&
-          !(keys[key] as Function)((item as { [key: string]: unknown })[key])
+          !(keys[key] as (i: unknown) => boolean)(
+            (item as { [key: string]: unknown })[key]
+          )
         ) {
           console.warn(
             `[Incorrect input] var: initOptions, key: ${key}, value: ${
@@ -348,6 +359,7 @@ const typeGuard = {
 };
 const isBoolean = (i: unknown): i is boolean => typeof i === "boolean";
 const isNumber = (i: unknown): i is number => typeof i === "number";
+const isString = (i: unknown): i is string => typeof i === "string";
 const isStringKeyObject = (i: unknown): i is { [key: string]: unknown } =>
   typeof i === "object";