OOM handling in C

[isaachier]

The h3 C library does not handle the case of malloc/calloc/realloc returning NULL in a robust manner. If assertions are enabled, the library crashes, otherwise it will use the NULL pointer leading to undefined behavior. While I understand the convenience of this design in the C library, not propagating OOM errors up the stack means binding code like this is not reliable:

h3-java/src/main/c/h3-java/src/jniapi.c

Line 44 in ed818d3

jclass oome = (**env).FindClass(env, "java/lang/OutOfMemoryError");

Users are likely to see a sudden fatal crash in the Java process and may not see any hint to the C assertion. Practically, consider using return codes to handle OOM up the stack for your C functions so you can handle them probably here.