show better error message when manifest.toml is corrupt

[zahash]

Steps to recreate the bug.

make a new project gleam new hellogleam

add some dependency, eg: glexer gleam add glexer

the gleam.toml should be looking like this

name = "hellogleam"
version = "1.0.0"

# Fill out these fields if you intend to generate HTML documentation or publish
# your project to the Hex package manager.
#
# description = ""
# licences = ["Apache-2.0"]
# repository = { type = "github", user = "username", repo = "project" }
# links = [{ title = "Website", href = "https://gleam.run" }]
#
# For a full reference of all the available options, you can have a look at
# https://gleam.run/writing-gleam/gleam-toml/.

[dependencies]
gleam_stdlib = ">= 0.36.0 and < 1.0.0"
glexer = ">= 0.7.0 and < 1.0.0"

[dev-dependencies]
gleeunit = ">= 1.0.0 and < 2.0.0"

the manifest.toml should be looking like this

# This file was generated by Gleam
# You typically do not need to edit this file

packages = [
  { name = "gleam_stdlib", version = "0.36.0", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "C0D14D807FEC6F8A08A7C9EF8DFDE6AE5C10E40E21325B2B29365965D82EB3D4" },
  { name = "gleeunit", version = "1.1.2", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleeunit", source = "hex", outer_checksum = "72CDC3D3F719478F26C4E2C5FED3E657AC81EC14A47D2D2DEBB8693CA3220C3B" },
  { name = "glexer", version = "0.7.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "glexer", source = "hex", outer_checksum = "4484942A465482A0A100936E1E5F12314DB4B5AC0D87575A7B9E9062090B96BE" },
]

[requirements]
gleam_stdlib = { version = ">= 0.36.0 and < 1.0.0" }
gleeunit = { version = ">= 1.0.0 and < 2.0.0" }
glexer = { version = ">= 0.7.0 and < 1.0.0"}

Now, delete the gleam_stdlib package in the manifest

# This file was generated by Gleam
# You typically do not need to edit this file

packages = [
  { name = "gleeunit", version = "1.1.2", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleeunit", source = "hex", outer_checksum = "72CDC3D3F719478F26C4E2C5FED3E657AC81EC14A47D2D2DEBB8693CA3220C3B" },
  { name = "glexer", version = "0.7.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "glexer", source = "hex", outer_checksum = "4484942A465482A0A100936E1E5F12314DB4B5AC0D87575A7B9E9062090B96BE" },
]

[requirements]
gleam_stdlib = { version = ">= 0.36.0 and < 1.0.0" }
gleeunit = { version = ">= 1.0.0 and < 2.0.0" }
glexer = { version = ">= 0.7.0 and < 1.0.0"}

run gleam add glexer

[zahash]

@lpil can this be merged?