Make stream failures sticky in LZ4FrameInputStream and LZ4BlockInputStream

[yawkat]

Fixes #101.

If a caller caught an IOException from either stream and kept reading, the stream could return data it had already rejected, or throw unchecked exceptions:

• Frame stream: a frame whose header checksum failed was decoded anyway. A block with a failed checksum or decompression was silently dropped. A skippable frame followed by a corrupt header led to an NPE.
• Block stream: a retry returned the bytes of a block whose checksum failed. available() could go negative, and read(byte[]) could throw IndexOutOfBoundsException.

Both classes now record the first failure. Any IOException or RuntimeException that escapes refill, nextFrameInfo or readBlock is stored, with RuntimeException wrapped in IOException. After that:

• read(), read(byte[],int,int), skip() and the frame stream's getExpectedContentSize()/isExpectedContentSizeDefined() throw IOException("Stream previously failed", cause). This check runs before any EOF early return.
• available() returns 0, and close() still works.
• The Javadoc of both classes describes this.

Behaviour change (release note): once any read, skip or header parse fails, the stream stays failed. That includes retrying after a transient error from the underlying stream, such as SocketTimeoutException. Such retries were already unsafe, because partially read input had been consumed.

Tests (they fail without the fix):

• Block stream: a corrupt block checksum, and an invalid originalLen (-1 and MAX_VALUE).
• Frame stream: a corrupt second-frame descriptor, a skippable frame followed by a corrupt header, a block checksum mismatch, the content-size getters after a failure, and a malformed first header surfacing as IOException.

Merge note: this may conflict with #128 (refill() header handling) and #133 (tests appended at the same place). The resolution is to keep both: #128's header logic goes at the start of refill0().

🤖 Generated with Claude Code

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Codecov Report

❌ Patch coverage is 87.17949% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.43%. Comparing base (f6e3304) to head (61dbbb7).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/java/net/jpountz/lz4/LZ4BlockInputStream.java	80.00%	3 Missing ⚠️
src/java/net/jpountz/lz4/LZ4FrameInputStream.java	91.66%	2 Missing ⚠️
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Additional details and impacted files

@@             Coverage Diff              @@
##               main     #145      +/-   ##
============================================
+ Coverage     79.76%   80.43%   +0.67%     
- Complexity      562      576      +14     
============================================
  Files            42       42              
  Lines          1838     1876      +38     
  Branches        247      253       +6     
============================================
+ Hits           1466     1509      +43     
  Misses          239      239              
+ Partials        133      128       -5     

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