Fix blank lines in content renderer (#8248)

CHANGELOG.md

@@ -15,6 +15,8 @@
   ([#8233](https://github.com/mitmproxy/mitmproxy/pull/8233), @ariel42)
 - mitmweb: Fix AVIF images and `image/vnd.microsoft.icon` favicons not rendering in the response tab.
   ([#8232](https://github.com/mitmproxy/mitmproxy/pull/8232), @ariel42)
+- mitmweb: Fix correctly displaying multiple blank lines in content renderer.
+  ([#8248](https://github.com/mitmproxy/mitmproxy/pull/8248), @vincentdehaan)
 
 ## 12 May 2026: mitmproxy 12.2.3
 

web/src/js/__tests__/components/contentviews/__snapshots__/HttpMessageSpec.tsx.snap

@@ -79,7 +79,9 @@ exports[`HttpMessage 1`] = `
       <div>
         rawdata
       </div>
-      <div />
+      <div>
+         
+      </div>
     </pre>
   </div>
 </DocumentFragment>
@@ -286,7 +288,9 @@ exports[`HttpMessage 3`] = `
       <div>
         rawdata
       </div>
-      <div />
+      <div>
+         
+      </div>
     </pre>
   </div>
 </DocumentFragment>
@@ -371,7 +375,9 @@ exports[`HttpMessage 4`] = `
       <div>
         rawdata
       </div>
-      <div />
+      <div>
+         
+      </div>
     </pre>
   </div>
 </DocumentFragment>

web/src/js/__tests__/components/contentviews/__snapshots__/LineRendererSpec.tsx.snap

@@ -15,7 +15,9 @@ exports[`ContentRenderer 1`] = `
       />
        Show more
     </button>
-    <div />
+    <div>
+       
+    </div>
   </pre>
 </DocumentFragment>
 `;

web/src/js/components/contentviews/ContentRenderer.tsx

@@ -30,7 +30,7 @@ const ContentRenderer = React.memo(function ContentRenderer({
                         Show more
                     </button>
                 ) : (
-                    <div key={i}>{line}</div>
+                    <div key={i}>{line || " "}</div>
                 ),
             )}
         </pre>