I have this code:

```
phi[t_] := t_0 + c*Exp[-k*t];
k = 1.5; t_0 = 60;
Thread[
Plot[Table[phi[t] /. c -> i, {i, -15, 15, 5}], {t, 0, 3},
PlotRange -> {45, 75}]]
```

Which, as expected, produces the plot:

However, mathematica is also spitting some weird error messages at me:

Thread::tdlen: Objects of unequal length in cannot be combined.

When I hover over the image in the error I get a list of a dozen other error messages:

RGBColor called with 1 argument; 3 or 4 arguments expected.

Coordinate Skeleton[77] should be a pair of numbers, or a Scaled or Offset form.

Coordinate Skeleton[77] should be a pair of numbers, or a Scaled or Offset form.

Coordinate Skeleton[77] should be a pair of numbers, or a Scaled or Offset form.

Coordinate Skeleton[52] should be a pair of numbers, or a Scaled or Offset form.

Coordinate Skeleton[77] should be a pair of numbers, or a Scaled or Offset form.

Coordinate Skeleton[77] should be a pair of numbers, or a Scaled or Offset form.

Coordinate Skeleton[77] should be a pair of numbers, or a Scaled or Offset form.

I searched for the three different types of error messages given and none of the results I found seem to be relevant to my “problem” (If you can call it that: my graph looks fine, mathematica is just complaining for some weird reason).

Is this a bug, or is there something subtle that I’m doing wrong?