Add fuzzing by way of ClusterFuzzLite

.clusterfuzzlite/Dockerfile

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+FROM gcr.io/oss-fuzz-base/base-builder
+RUN apt-get update && apt-get install -y make autoconf automake libtool cmake \
+                      pkg-config curl check
+COPY . $SRC/simpleson
+COPY .clusterfuzzlite/build.sh $SRC/build.sh
+COPY .clusterfuzzlite/fuzzer.cpp $SRC/fuzzer.cpp
+WORKDIR simpleson

.clusterfuzzlite/build.sh

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+#!/bin/bash
+mkdir fuzz-build
+cd fuzz-build
+cmake -DCMAKE_VERBOSE_MAKEFILE=ON ../
+make V=1 || true
+
+$CXX $CXXFLAGS $LIB_FUZZING_ENGINE $SRC/fuzzer.cpp -Wl,--whole-archive $SRC/simpleson/fuzz-build/libsimpleson.a -Wl,--allow-multiple-definition -I$SRC/simpleson/  -o $OUT/fuzzer

.clusterfuzzlite/fuzzer.cpp

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+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "json.h"
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+    if (size == 0) {
+        return 0;
+    }
+
+    // Copy input data to a null-terminated string
+    char* input = new char[size + 1];
+    memcpy(input, data, size);
+    input[size] = '\0';
+
+    try {
+        json::jobject::parse(input);
+    } catch (...) {
+        // Catch all exceptions thrown by the target code
+    }
+
+    delete[] input;
+
+    return 0;
+}

.clusterfuzzlite/project.yaml

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+language: c++

.github/workflows/cflite_pr.yml

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+name: ClusterFuzzLite PR fuzzing
+on:
+  workflow_dispatch:
+  pull_request:
+    branches: [ master ]
+permissions: read-all
+jobs:
+  PR:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        sanitizer: [address]
+    steps:
+    - name: Build Fuzzers (${{ matrix.sanitizer }})
+      id: build
+      uses: google/clusterfuzzlite/actions/build_fuzzers@v1
+      with:
+        sanitizer: ${{ matrix.sanitizer }}
+        language: c++
+        bad-build-check: false
+    - name: Run Fuzzers (${{ matrix.sanitizer }})
+      id: run
+      uses: google/clusterfuzzlite/actions/run_fuzzers@v1
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}
+        fuzz-seconds: 100
+        mode: 'code-change'
+        report-unreproducible-crashes: false
+        sanitizer: ${{ matrix.sanitizer }}