[pron]

1. You can get an OOM error (or a stack overflow) in most languages (including Rust).

2. Safety-critical hard realtime systems require far more determinism guarantees than a language/runtime alone can provide. For example, they require deterministic scheduling of threads (usually round robin with very strong prioritization guarantees and bounded task-switching latence), and so require a realtime OS. Also, safety-critical realtime systems have ways of guaranteeing bounded memory growth, for both the stack and the heap. These exist in specialized languages for realtime such as SPARK (an Ada variant) and SCADE.

3. Java is actually used in safety-critical hard realtime systems, including avionics, but in a special, hard realtime JVM that has different kinds of deterministic guarantees (when run on a realtime OS), including memory allocation, scheduling and hard deadlines for asynchronous events (see https://www.aicas.com/cms/en/rtsj). What's particularly cool about realtime Java is that it allows for a safe mix of realtime and non-realtime threads, as even in realtime systems, the actual realtime part is usually a small portion of the program.