use at() to get exceptions

I encountered a new error from an out-of-bounds access on a
terrain array, which I wasn't able to record because it caused
a segfault, not throwing an exception. If the error happens again,
I want to catch and record it.

src/tools/vector2d.hpp

@@ -40,10 +40,10 @@ public:
 		}
 	public:
 		Type& operator[](size_t x) {
-			return ref.data[ref.w * y + x];
+			return ref.data.at(ref.w * y + x);
 		}
 		const Type& operator[](size_t x) const {
-			return ref.data[ref.w * y + x];
+			return ref.data.at(ref.w * y + x);
 		}
 		row_ref operator=(row_ref&& other) {
 			row_ref& me = *this;
@@ -94,10 +94,10 @@ public:
 		}
 	public:
 		Type& operator[](size_t y) {
-			return ref.data[ref.w * y + x];
+			return ref.data.at(ref.w * y + x);
 		}
 		const Type& operator[](size_t y) const {
-			return ref.data[ref.w * y + x];
+			return ref.data.at(ref.w * y + x);
 		}
 		col_ref operator=(col_ref&& other) {
 			col_ref& me = *this;
@@ -139,7 +139,7 @@ public:
 		const_row_ref(const vector2d<Type, Alloc>& ref, size_t row) : ref(ref), y(row) {}
 	public:
 		const Type& operator[](size_t x) const {
-			return ref.data[ref.w * y + x];
+			return ref.data.at(ref.w * y + x);
 		}
 	};
 	class const_col_ref {
@@ -149,7 +149,7 @@ public:
 		const_col_ref(const vector2d<Type, Alloc>& ref, size_t col) : ref(ref), x(col) {}
 	public:
 		const Type& operator[](size_t y) const {
-			return ref.data[ref.w * y + x];
+			return ref.data.at(ref.w * y + x);
 		}
 	};
 	col_ref operator[](size_t x) {

src/universe/universe.cpp

@@ -821,19 +821,19 @@ bool cCurTown::is_on_map(short x, short y) const {
 }
 
 auto cCurOut::operator [] (size_t i) -> arr_96& {
-	return out[i];
+	return out.at(i);
 }
 
 auto cCurOut::operator [] (size_t i) const -> const arr_96& {
-	return out[i];
+	return out.at(i);
 }
 
 ter_num_t& cCurOut::operator [] (location loc) {
-	return out[loc.x][loc.y];
+	return out.at(loc.x).at(loc.y);
 }
 
 const ter_num_t& cCurOut::operator [] (location loc) const {
-	return out[loc.x][loc.y];
+	return out.at(loc.x).at(loc.y);
 }
 
 void cCurOut::writeTo(std::ostream& file) const {