fix(ui): prevent log viewer crash on malformed stream packets issue #26023

[LBaronceli]

##Description
Fixes [ISSUE #26023 ]
The log stream reader in ApplicationsService blindly parses JSON chunks and accesses .result. If a malformed packet (e.g., undefined or null result) arrives—which can happen during backend race conditions when merging streams from multiple replicas—the UI crashes with a TypeError.
This PR adds a defensive check to ensuring the parsed result is valid before passing it to the UI component.

##Changes

• Updated getContainerLogs in applications-service.ts to include a try...catch block around JSON parsing.
• Added a filter to discard null or undefined entries before they reach the subscriber.
• Added console.error logging for parsing failures to aid in future debugging.

##Verification

1. Simulated the issue by injecting random undefined packets into the log stream.
2. Verified that the UI no longer crashes and continues to stream valid logs.

##Steps I used to re-create the issue:

1. Created multiple replicas.
2. Made them produce logs continually with:

kubectl patch deployment guestbook-ui -n default --type='strategic' -p '{"spec":{"replicas":5,"template":{"spec":{"containers":[{"name":"guestbook-ui","command":["/bin/sh","-c"],"args":["echo \"Starting log generator...\"; while true; do echo \"$(date -Iseconds) - Log entry from $(hostname) - Random: $RANDOM\"; done"]}]}}}}'

3. Changed the entries code in ui/src/app/shared/services/applications-service.ts ~ line 321 to add random errors:

const entries = requests.loadEventSource(`/applications/${applicationName}/logs?${search.toString()}`).pipe(
            map(data => {
                // Randomly inject a bad packet to reproduce Issue
                if (Math.random() < 0.05) {
                    console.log('Simulating malformed backend response (Issue #26023 reproduction)...');
                    return undefined as unknown as models.LogEntry;
                }
                return JSON.parse(data).result as models.LogEntry;
            })
        );

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• The title of the PR conforms to the Title of the PR
• I've included "Closes [ISSUE #]" or "Fixes [ISSUE #]" in the description to automatically close the associated issue.
• I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• Does this PR require documentation updates?
• I've updated documentation as required by this PR.
• I have signed off all my commits as required by DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My build is green (troubleshooting builds).
• My new feature complies with the feature status guidelines.
• I have added a brief description of why this PR is necessary and/or what this PR solves.
• Optional. My organization is added to USERS.md.
• Optional. For bug fixes, I've indicated what older releases this fix should be cherry-picked into (this may or may not happen depending on risk/complexity).

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