Fix API bugs exercised by test/deep_api_bugs.cpp

- api_fpa.cpp: add RETURN_Z3(nullptr) after SET_ERROR_CODE in Z3_mk_fpa_sort to prevent fall-through to mk_float_sort with invalid params
- api_seq.cpp: add null check for str in Z3_mk_string; add null check for str when sz>0 in Z3_mk_lstring; add lo<=hi validation in Z3_mk_re_loop
- api_array.cpp: add explicit n==0 validation in Z3_mk_array_sort_n
- api_solver.cpp: rename local variable 'c' to avoid shadowing Z3_context param in Z3_solver_propagate_created/decide/on_binding; move init_solver call inside file-exists branches of Z3_solver_from_file
- api_ast.cpp: add null check for target in Z3_translate; add null check for _from/_to arrays when num_exprs>0 in Z3_substitute
- api_model.cpp: add CHECK_NON_NULL(m) in Z3_add_func_interp; add CHECK_NON_NULL(a) in Z3_model_get_const_interp; add null check for target in Z3_model_translate
- api_opt.cpp: add null check for weight string in Z3_optimize_assert_soft
- api_quant.cpp: add num_patterns==0 validation in Z3_mk_pattern

Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>

src/api/api_array.cpp

@@ -38,6 +38,10 @@ extern "C" {
         Z3_TRY;
         LOG_Z3_mk_array_sort_n(c, n, domain, range);
         RESET_ERROR_CODE();
+        if (n == 0) {
+            SET_ERROR_CODE(Z3_INVALID_ARG, "array sort requires at least one domain sort");
+            RETURN_Z3(nullptr);
+        }
         vector<parameter> params;
         for (unsigned i = 0; i < n; ++i) params.push_back(parameter(to_sort(domain[i])));
         params.push_back(parameter(to_sort(range)));