fix: 탐색 - 시그니처 썸네일 가져오기 버그 해결 (#234)

## 요약
fix: 탐색 - 시그니처 썸네일 가져오기 버그 해결
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## 작업 내용
시그니처 이미지 에러에 대한 예외처리 구성
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## 참고 사항

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## 관련 이슈

- Close #이슈번호

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src/search/search.service.ts

@@ -86,6 +86,7 @@ export class SearchService{
     for (let i = 0; i < signatureEntities.length && i < 20; i++) {
       const signature = signatureEntities[i];
       const signatureCover = await this.getSignatureCover(signature);
+      if(signatureCover) signatureCovers.push(signatureCover);
 
       signatureCovers.push(signatureCover);
     }
@@ -103,7 +104,7 @@ export class SearchService{
       const resultCovers = [];
       for(const signature of resultSignatures){
         const signatureCover = await this.getSignatureCover(signature);
-        resultCovers.push(signatureCover);
+        if(signatureCover) resultCovers.push(signatureCover);
       }
       return resultCovers;
 
@@ -125,8 +126,12 @@ export class SearchService{
 
     // 시그니처 썸네일 이미지 가져오기
     signatureCover.date = await SignatureEntity.formatDateString(signature.created);
+
     const signatureImageKey = await SignaturePageEntity.findThumbnail(signature.id);
-    signatureCover.image = await this.s3Service.getImageUrl(signatureImageKey);
+    if(signatureImageKey != null ){
+      signatureCover.image = await this.s3Service.getImageUrl(signatureImageKey);
+    }
+    else return null;
 
     // 시그니처 작성자 프로필 이미지 가져오기
     const userProfileImageEntity = await this.userService.getProfileImage(signature.user.id);

src/signature/domain/signature.page.entity.ts

@@ -55,8 +55,13 @@ export class SignaturePageEntity extends BaseEntity {
         },
       });
 
-      console.log("썸네일 이미지: ",firstPage.image);
-      return firstPage.image;
+      console.log("첫번째 페이지: ",firstPage);
+
+      if(firstPage == null) return null;
+      else {
+        console.log("썸네일 이미지: ",firstPage.image);
+        return firstPage.image;
+      }
 
     } catch (error) {
       console.log('Error on findThumbnail: ', error);

src/signature/signature.service.ts

@@ -94,10 +94,10 @@ export class SignatureService {
   async homeSignature(userId: number): Promise<HomeSignatureDto[]> {
     try {
       console.log('userId; ', userId);
-      const homeSignatureList: HomeSignatureDto[] = await this.findMySignature(
+      return this.findMySignature(
         userId,
       );
-      return homeSignatureList;
+
     } catch (error) {
       // 예외 처리
       console.error('Error on HomeSignature: ', error);