Mesh.vertices is too small. The supplied vertex array has less vertices than are referenced by the triangles array.
UnityEngine.Mesh:set_vertices(Vector3[])
TMPro.TextMeshProUGUI:GenerateTextMesh() (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMPro_UGUI_Private.cs:4097)
TMPro.TextMeshProUGUI:OnPreRenderCanvas() (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMPro_UGUI_Private.cs:1656)
TMPro.TextMeshProUGUI:Rebuild(CanvasUpdate) (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TextMeshProUGUI.cs:209)
UnityEngine.Canvas:SendWillRenderCanvases()

Mesh.uv is out of bounds. The supplied array needs to be the same size as the Mesh.vertices array.
UnityEngine.Mesh:set_uv(Vector2[])
TMPro.TextMeshProUGUI:GenerateTextMesh() (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMPro_UGUI_Private.cs:4098)
TMPro.TextMeshProUGUI:OnPreRenderCanvas() (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMPro_UGUI_Private.cs:1656)
TMPro.TextMeshProUGUI:Rebuild(CanvasUpdate) (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TextMeshProUGUI.cs:209)
UnityEngine.Canvas:SendWillRenderCanvases()

Mesh.uv2 is out of bounds. The supplied array needs to be the same size as the Mesh.vertices array.
UnityEngine.Mesh:set_uv2(Vector2[])
TMPro.TextMeshProUGUI:GenerateTextMesh() (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMPro_UGUI_Private.cs:4099)
TMPro.TextMeshProUGUI:OnPreRenderCanvas() (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMPro_UGUI_Private.cs:1656)
TMPro.TextMeshProUGUI:Rebuild(CanvasUpdate) (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TextMeshProUGUI.cs:209)
UnityEngine.Canvas:SendWillRenderCanvases()

Mesh.colors is out of bounds. The supplied array needs to be the same size as the Mesh.vertices array.
UnityEngine.Mesh:set_colors32(Color32[])
TMPro.TextMeshProUGUI:GenerateTextMesh() (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMPro_UGUI_Private.cs:4101)
TMPro.TextMeshProUGUI:OnPreRenderCanvas() (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMPro_UGUI_Private.cs:1656)
TMPro.TextMeshProUGUI:Rebuild(CanvasUpdate) (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TextMeshProUGUI.cs:209)
UnityEngine.Canvas:SendWillRenderCanvases()