ModelSim error: unexpected internal error in Questa

Dear all,

I'm trying to simulate the following piece of code:

module peak_detect #(
	parameter BATCH_SIZE,
	parameter DATA_WIDTH
)(
	input		wire							clk,
	input		wire							reset,
	input		wire							sink_sop,
	input		wire							sink_eop,
	input		wire							sink_valid,
	input		wire	[DATA_WIDTH-1:0]	sink_re,
	input		wire	[DATA_WIDTH-1:0]	sink_im,
	output	bit							source_sop,
	output	bit							source_eop,
	output	bit							source_valid,
	output	int							source_freq,
	output	int							source_mag,	
	output	int							source_phaseA,
	output	int							source_phaseB
);
 
// more parameters
localparam BIN_WIDTH = 10;
localparam NPEAKS = 4;
localparam shortint EXPEAKS[NPEAKS] = '{200, 400, 600, 800};
localparam PEAKDEV = 50;
 
typedef struct {
	shortint	bin;
	byte		delta;
	int		re[0:2];
	int		im[0:2];
	int		mag[0:2];
} chunk;
 
task automatic chunk_reset(ref chunk chnk);
	chnk.bin			<= 0;
	chnk.delta		<= 0;
	for (byte i = 0; i < 3; i++)
	begin
		chnk.re[i]		<= 0;
		chnk.im[i]		<= 0;
		chnk.mag[i]		<= 0;
	end
endtask
 
task automatic chunk_shift(ref chunk chnk);
	chnk.bin			<= chnk.bin + 1;
	for (byte i = 0; i < 2; i++)
	begin
		chnk.re[i]		<= chnk.re[i+1];
		chnk.im[i]		<= chnk.im[i+1];
		chnk.mag[i]		<= chnk.mag[i+1];
	end
	chnk.re[2]		<= sink_re;
	chnk.im[2]		<= sink_im;
	chnk.mag[2]		<= hypot(sink_re, sink_im) <<< 8;
endtask
 
chunk										buffer;
chunk										peaks[0:NPEAKS-1];
bit	[$clog2(BATCH_SIZE)-1:0]	sink_pos;
bit										sink_done;
bit	[$clog2(NPEAKS)-1:0]			source_pos;
bit										source_done;
 
always @(posedge clk)
begin
	if (reset || sink_eop)
	begin
		chunk_reset(buffer);
		for (byte i = 0; i < NPEAKS; i++)
			chunk_reset(peaks[i]);
		sink_pos			<= 0;
		sink_done		<= 0;
		source_pos		<= 0;
		source_done		<= 0;
		source_valid	<= 0;
	end
	else if (!sink_done && sink_valid)
	begin
		for (byte i = 0; i < NPEAKS; i++)
			if (EXPEAKS[i]-PEAKDEV <= sink_pos && sink_pos < EXPEAKS[i]+PEAKDEV && buffer.mag[1] > peaks[i].mag[1])
				peaks[i] 		<= buffer;
		chunk_shift(buffer);
		sink_done		<= (sink_pos == BATCH_SIZE - 1) ? 1 : 0;
		sink_pos			<= sink_pos + 1;
	end
	else	
	begin
		source_valid	<= 0;
	end
end
 
endmodule

The code is perfectly synthesisable in Quartus Prime Lite, but ModelSim returns an error when compiling: "Error: C:/[path]/peak_detect.sv(35): Questa has encountered an unexpected internal error: ../../src/vlog/vgencode.c(118)"

If I comment out the calling of the task, ModelSim still gives the same error. So it's something with the task, but I don't know what exactly. Does anyone have an idea how to solve this problem? Am I doing really bad things with my code, or is it a bug in ModelSim?