How to suitably avoid RangeErrors when "looking around" this 2D array? - multidimensional-array

Question

I have a 2D array structure to represent a grid of tiles that is a part of the game I am making. One aspect of the game is that the grid is filled in in a somewhat random fashion, based on analysis of a text file. Right from the outset though, I already realised that just leaving it be pretty much randomly done like this without sticking in some kind of validity checks or prevention mechanism, to stop really badly configured grid from forming, would not work out. The main problem I want to avoid is too many tiles that would be untraversable being close together, potentially severing chunks of the grid from the rest.
The idea I came up with to try avoid some really bad grids is to check when assigning a tile value to each "grid square" during generation with logic like this
if (tileBeingInserted.isTraversable()) {
//all is well
return true;
} else {
//we may have a problem, are there too many untraversables nearby?
//Proceed to check all squares "around" the current one.
}
To be clear, checking around the current square means checking the square immediately adjacent in each of the 8 cardinal directions. Now, my problem is that I am trying to reason out how to code this so that it will certainly not give a RangeErrorat any point or at least catch it and recover if it must. As an example, you could clearly take one of the corner squares to be the worst scenario in the sense that only 2 of the squares the algorithm would want to check are within the array's bounds. Naturally, if a RangeErrorhappens for this reason I just want the program to progress onward without issue so the structure
try {
//check1
//check2...8
} catch (RangeError e) {
}
is unacceptable because as soon as a single out of range square is tested the code falls out of the check block. An alternative I thought of, but do not like because of its messiness, would be to individually wrap each check in a try-catch and yes that would work I guess but that's some horrid looking code...so can anyone help me out here? Is there perhaps a different angle from which to come at this problem of avoiding the RangeErrors that I am not seeing?

Answer 1

So my code for testing whether another untraversable tile should be placed has shaped up like this:
bool _tileFitsWell(int tileTypeInt, int row, int col)
{
//...initialise some things, set stuff up
...
if (tile.traversable == true) {
//In this case a new traversable tile is being put in, so no problems.
return true;
} else {
//begin testing what tiles are around the current tile
//Test NW adjacent
if (row > 0 && col > 0) {
temp = tileAt(row - 1, col - 1);
if (!temp.traversable) {
strikeCount++;
}
}
//Test N adjacent
if (row > 0) {
temp = tileAt(row - 1, col - 1);
if (!temp.traversable) {
strikeCount++;
}
}
//Test NE adjacent
if (row > 0 && col < _grid[0].length - 2) {
temp = tileAt(row - 1, col 1);
if (!temp.traversable) {
strikeCount++;
}
}
//Test W adjacent
if (col > 0) {
temp = tileAt(row, col - 1);
if (!temp.traversable) {
strikeCount++;
}
}
}
return strikeCount < 2;
}
The code inside each "initial" if-statement (the ones that check row and col) is a bit pseudocode-ish for simplicity's sake. As I explained in a previous comment, the reason why I don't need to check tiles in the other 4 cardinal directions is since these checks are done while filling the map, tiles in those positions will always be either uninitialised or just out of bounds, depending on what tile the function is called to check at a given time.