I replicated your error with your code. I looked at the test suite for Tk in the t/photo.t, and they include use Tk::PNG; use Tk::JPEG; (or equivalent conditional require's), so I successfully tried code with the two extra use statements:

use strict;
use warnings;
use Tk;
use Tk::PNG;
use Tk::JPEG;
my @arr;
push @arr, { name => 'sample.gif', type => 'image/gif'};
push @arr, { name => 'sample.png', type => 'image/png'};
push @arr, { name => 'sample.jpg', type => 'image/jpeg'};
foreach my $fh (@arr) {
  my $f = $fh->{name};
  my $t = $fh->{type};
  eval {
    my $mw = MainWindow->new;
    my $lbl = $mw->Label;
    my $photo = $mw->Photo(-file=>$f); #, -format=>$t );
    $lbl->configure(-image=>$photo);
    $lbl->pack;
    MainLoop;
    1;
  } or do {
    warn "here: $@\n";
  };
}
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update: I was curious about the -format, since the mime-types I had tried (based on commented-out code) didn't work. the t/photo.t showed method $photo->formats(), so I printed those => jpeg, png, bmp, xpm, xbm, gif, PPM. So, to get -format to work with my code, it should be as follows (which still works):

use strict;
use warnings;
use Tk;
use Tk::PNG;
use Tk::JPEG;
my @arr;
push @arr, { name => 'sample.gif', type => 'gif'};
push @arr, { name => 'sample.png', type => 'png'};
push @arr, { name => 'sample.jpg', type => 'jpeg'};
foreach my $fh (@arr) {
  my $f = $fh->{name};
  my $t = $fh->{type};
  eval {
    my $mw = MainWindow->new;
    my $lbl = $mw->Label;
    my $photo = $mw->Photo(-file=>$f, -format=>$t );
    print join ", ", $photo->formats(), "\n";
    $lbl->configure(-image=>$photo);
    $lbl->pack;
    MainLoop;
    1;
  } or do {
    warn "here: $@\n";
  };
}
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